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Why Is My AC Blowing Warm Air? Common Causes and Fixes

September 19, 2025
Modified on September 10, 2025

With average summer highs routinely in the mid-80s, AC problems in summer can quickly turn your Abington home into an uncomfortable swamp. We’ll explore some of the most common causes of your AC blowing warm air, troubleshooting tips, and who to call for professional air conditioner services in Abington, PA.

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Top Reasons Your AC Is Blowing Hot Instead of Cold

Wondering why your AC isn’t cooling? These common issues could be the culprit.

Thermostat Settings Issues

If you’re having trouble with your AC temperature, the easiest place to start is with your thermostat. Check that it’s set to the right temperature and has full power. For some models, this might include checking or replacing the batteries.

If everything looks correct, the culprit could be the location of your thermostat. Thermostats placed directly in front of fans and air vents, beside windows and doors, or in direct sunlight can all provide faulty measurements that trigger your HVAC system. For example, if your thermostat is in front of the AC vent, it can read the room as being colder than it really is, signaling your AC to turn off early.

Dirty or Clogged Air Filters

Dirty air filters in your AC are one of the most common causes of air conditioner problems. When filters become dirty or clogged, your AC has to work harder to push air through the system. This increases wear and tear and can cause the system to shut off to prevent overheating.

Energy Star recommends checking your air filters at least once a month and replacing them every three months or as recommended by the manufacturer. If you live in a home with pets or smokers, or if there’s a lot of dust, dirt, pollen, or other contaminants in your area, you may want to change your filters more frequently.

Refrigerant Leaks

Refrigerants facilitate the heat transfer process in your AC, moving heat from inside your home and depositing it outside. When everything’s working properly, the level of refrigerant in the system stays the same. However, a refrigerant leak can cause levels to drop, meaning your AC doesn’t have enough fluid to move heat out of your home. Common refrigerant leak symptoms include your air conditioner blowing hot air, rising energy bills, ice buildup around your AC, and a chemical smell.

In addition to causing your AC to blow warm air, refrigerant leaks are a health hazard. If you notice liquid pooling on or around your AC, or if you smell a sweet, chemical odor from your AC, turn off the system immediately. Evacuate the area, open the windows, and call a professional for emergency AC repair.

Electrical or Compressor Issues

The compressor is responsible for circulating refrigerant through your AC, keeping the cooling process flowing smoothly. If this component breaks down, your AC can’t cool anymore and may start blowing warm air.

Always call a pro for any electrical or compressor issues. Attempting DIY fixes not only risks breaking the system further, but it can also pose a health hazard.

Frozen Evaporator Coils

In most systems, your AC evaporator coil is found inside the air handler unit. When evaporator coils freeze, they prevent your AC from properly moving heat out of your home.

Coils can freeze over due to lack of airflow or low refrigerant levels, meaning a frozen evaporator coil is often a secondary problem. Turning off the AC and allowing the coil to thaw can get rid of the ice buildup, but you’ll also need to check your filters or call a pro to inspect the refrigerant.

AC Tip: If your air conditioner is blowing warm air, it’s best to turn it off. Continuing to run the system can wear out key components and lead to costly repairs. Depending on the cause of the issue, running a broken air conditioner may also pose a health hazard or cause a fire.

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Preventative AC Maintenance Tips to Avoid Warm Air Issues

Preventative maintenance is key to prolonging the life of your air conditioner, avoiding repairs, and keeping your home cool and comfortable. Try the following Philadelphia AC maintenance tips to keep your system running smoothly:

  • Check air filters monthly and replace filters at least every three months.
  • Schedule annual AC maintenance to clean and tune-up your unit. It’s recommended to book maintenance in the spring before the heavy-use season to get your AC ready for summer.
  • Clean the outdoor unit, removing any leaves and other debris from around the vents.
  • Check thermostat settings and aim for an energy-efficient setting to reduce HVAC wear and tear. Smart thermostats can help maintain efficient temperatures while you’re away without compromising comfort.

Your HVAC pro will also come prepared with a professional AC maintenance task list. This typically includes lubricating all moving parts, checking refrigerant levels, cleaning the condensate drain, and checking electrical components.

When to Call for Professional AC Repair in Philadelphia

If you’re worried about AC issues, you can troubleshoot by replacing the air filters and checking your thermostat. However, if your thermostat is set correctly but your AC still isn’t cooling, it’s time to call for professional AC repairs. At Chud Cooling & Heating, we serve the greater Abington area to deliver expert HVAC repairs near you.

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Schedule AC Service with Chud Cooling & Heating Today

From emergency AC repairs to preventative maintenance, we offer expert knowledge and great customer service to keep your AC running smoothly. Contact us today to book your next appointment and get your home ready for summer.

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Customer Testimonials

Check Out Our 5-Star Reviews!


  • “I had a great experience with Chud. Lewis and Sebastian did a fantastic job. They were communicative and on time, explained everything that they would be doing to clean my HVAC ductwork, answered all of my questions, were honest about not being able to properly clean my dryer vent, and cleaned up after they were done. They also went above and beyond, even cleaning dust from each slat of the return vent. Highly recommend.”

    – Jay C.
  • “We have been a customer of Chud Air Conditioning, Heating & Duct Cleaning for many years and have always had a very satisfying experience. The technicians have been very responsive during emergencies, are informative, and professional. Shane was our recent service technician who replaced our water heater. Shane was excellent, very thorough, friendly, and dependable. I would not hesitate to use them again and don’t forget to ask for Shane!”

    – Michael M.
  • “We rely on Chud Duct Cleaning to perform our regular duct cleaning in our home. Your service technicians Lewis and Sebastian arrived promptly, introduced themselves and got right to work. Our home has many vents behind and under furniture, which was moved and replaced as if nothing ever happened. My home was carefully prepared and respected throughout the entire process. An access panel was replaced for a more pleasant look and better access in the future. I will not hesitate to use this company for service again.”

    – Catherine C.
  • “They came to service my heater and clean my ducts. They were super respectful of my property, thourough with their work, and carefully explained everything to me. My system is falling into disrepair. I could clearly see the rust and hear the problems they found. They recommended a variety of possible solutions from temporary furnace repairs to a new HVAC system. No pressure. I have a lot to think about, but it is good to know I have found someone I can trust to do the job.”

    – Phyllis W.
  • “Lewis and Sebastian were professional, knowledgeable and polite, and worked diligently over the course of two days to clean and sanitize the immense ductwork system at this location. They took the time to explain the process in detail, and were extremely aware of the need to treat a customer’s home as if it were their own. This was my second experience with Chud, and I won’t hesitate to call them again in the future.”

    – BC.
  • “Had a new heater and ac installed. Very pleased with entire process, from troubleshooting the old system to choosing the new to installation. Rich had patience with all my questions about the new system and helped me to understand the differences I should expect with the new. Matt and John did an outstanding job pulling out the old and installing the new. They got there on time and got right to work. Very professional technicians. Overall, a top notch job at a fair price. I highly recommend Chud.”

    – Phil W.

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